No abstract

Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90–120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at Ev + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10−17 cm2. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

Interactions of hydrogen with titanium have been studied in Ti-doped n-type crystalline Si using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen plasma treatments of the samples at room temperature have resulted in the suppression of DLTS signals due to interstitial Ti atoms (Tii) and the appearance of three strong DLTS peaks, which are related to three different Ti-H defects. After annealing of the hydrogenated samples at 150 °C in nitrogen, the signals due to Tii and two of the three H-related defects were not detected in the spectra showing that almost complete passivation of all electrically active defects occurred.

Copper germanate has been examined by synchrotron x-ray powder diffraction at high pressure in a diamond anvil cell at pressures up to 2u) kbar , and by infrared spectroscopy to 162 kbar. These concur in showing a phase transition at 66-73 kbar: the x-ray powder diffraction data have been indexed successfully on the basis of a P2,/a cell. deduced from a model of lhe phase change in which germanate chains slip relative to each other along their axes.Slow changes in diffraction pattern from 11C-220 kbar suggest existence of a further, very sluggish, phase change. CuGeO, turns black near 5 kbar due to a band shift.Contraction of the orthorhombic cell constants of the initial phase is markedly anisotropic, the principal changes being in the plane which contains the long Cu-0 bonds. These are twice as easily compressed as the short Cu-0 bonds.

No abstract